Compaction Behaviour of Lateritic Soils Stabilized with Blends of Groundnut Shell Ash and Metakaolin

The study investigates the potential of groundnut shell ash (GSA) - Metakaolin (MK) blend for stabilization of lateritic soil, with a view to improving the properties of lateritic soils for road construction. In flexible pavements lateritic soil are used as materials for sub-grade and sub-base construction. In some cases lateritic soils pose serious challenges when encountered as road construction materials due to the presence of clay. The soil was classified as A-2-6(0) and CL according to the American Association of State Highway and Transport Officials (AASHTO) and Unified Soil Classification System (USCS) Classifications. Chemical analysis revealed that the soil is lateritic soil due to the Silica - sesquioxide ratio which falls within the ranged 1.33 to 2.00 as defined by Bell (1993). The soil was stabilized with increment of 2-10% GSA and 5-25%MK by weight of the dry soil. The laboratory tests were carried out using three energy levels such as British Standard light (BSL), British Standard heavy (BSH) and West African Standard (WAS). California bearing ratio (CBR), Unconfined Compressive strength (UCS), and Compaction test were also carried out. The result obtained showed a decrease in plasticity index (PI), Liquid limit (LL), plastic limit (PL), and water absorption. There was an increase in Maximum dry density (MDD) with increase in GSA and MK contents in the mix proportions used. There was also improvement in the CBR which resulted to an optimum of 36%, 154% and 81% using BSL, BSH and WAS compactive effort respectively; which met the acceptable requirement for sub-grade, sub-base and base course of highly trafficked roads in Nigeria. The UCS values at 7 days cured of 402, 731 and 530kN/m2 fell short of 1710kN/m2 and 1034.25kN/m2 evaluated in the criteria recommended by TRRL road Note: 31 and Nigerian General Specification for Road and Bridges. The durability of specimen met 80% resistant to loss in strength. Keywords: Metakaolin, Subgrade, Sesquioxide, California bearing ratio, Unconfined compressive strengt

Increase the Strenght of Base and Subbase of Flexible Pavement by adding Fledspar as additive material

The strength and durability of the flexible pavement is highly dependent on the quality of the aggregate material used for base and subbase layers. This is can be understand since  95 percent of the weight-volume of the base and subbase layer is aggregate. Therefore using a good quality and strong base and subbase material is very important. In this paper, which is a report of a reseacrh,  Feldspar is used as stabilizer of base and subbase materlias of flexible pavement. Feldspar  is a group rock-ftant forming tectosilicate minerals that made up about 41% of the earth’s continental crust by weight. 5 to 25% of Feldspar with increment of 5% by weight of the base and also subbase were added. Direct Shear and California Baring Ratio (CBR) test were conducted., beside water content and dry density test. The results of direct shear  test show that cohesion of base and subbase materials decrease from 0,164 kg/cm2 of original base and subbase materials become 0,01 kg/cm2 for base and subbase material after adding with 25% of Feldspar, and angle of inernal friction increase from 47,670 become 49,800. Meanwhile the results of CBR test show that CBR value of base increase from 30% to 86,40%, as well as for subbase increase from 21,50% to 87,30% after adding with 15% of Feldspar. It can be concluded that adding aggregate of base and subbase with Feldspar the strenght improve signicantly, and the influence is the strengthening of the base and subbase layers

Evaluation of major causes of road accidents along North–East Highway, Nigeria

A major road link in the North-Eastern region of Nigeria is the Bauchi – Maiduguri highway that is a 425 km road that links a section of the north east region to other regions of Nigeria. The goods and services to the region are basically transported by road. This has increased vehicular traffic that resulted in increased road accident rates over the years. It is paramount to investigate the major causes of vehicle accidents on this highway as much has not been done to investigate accident cases on the route. The five year accident record on that route was obtained from the Federal Road Safety Corp of Nigeria, the Nigeria Police traffic unit, and the Nigeria union of road traffic workers. The study indicated that speed violation by drivers and bad road conditions contributes greatly in the rate of accidents along the route. Hence the study recommends better road maintenance culture and more sensitization of the road users and enforcement of speed limit

The determination of the texture depth, skidding resistance and roughness index of various bituminous road surfaces

The determination of the skidding resistance of a bituminous pavement surface depends on the texture depth of the road surface. The texture depth is a measure of the macrotexture of the pavement surface, which is the coarse component of the surface aggregate and determine by sand patch test (SPT). While the microtexture, which is the measure of the aggregate interstices referred to as the resistance to polishing (PSV) of the aggregate, is determined by the British pendulum test (PTV). The roughness of the road surface is a determining factor for the smoothness of the road surface, and was determined by using the walking profilometer. The study was conducted on jalan Tebrau, jalan Pontian and Batu Pahat, 180 test points were investigated for the three tests. This study is aim at determining the minimum skidding resistance, texture depth, and roughness index of various bituminous road surfaces, and there correlation. The results obtained from the study shows a fair correlation between the texture depth and the roughness index of the chipseal road surfaces. But the general trend is that the higher the texture depth (TD), the higher the roughness index (IRI) and the skid resistance (SR), except with the new ACW 14 where at high SR the IRI is low, as the SR depends on the microtexture

Binder characterization and performance of warm stone mastic asphalt mixture

The conventional stone mastic asphalt (SMA) is normally produced at high temperature (180oC) that consumes fuel, increases cost, and generates heat with emissions of green house gases. This study investigated the potential of producing stone mastic asphalt at lower temperature (130oC) termed as warm stone mastic asphalt (WSMA) against the normal high mixing temperature. Three grades of bitumen 80/100, 60/70 and PG 76-22 were investigated. A long chain aliphatic hydrocarbon Sasobit wax (SW) was used as an additive to reduce the mixing temperature. The Sasobit wax was incorporated at 0.5%, 1%, 1.5%, 2%, 2.5% and 3% of bitumen content. The empirical tests were conducted on 105 samples of the three binder types, which include penetration test at 10oC and 25oC. Softening point test, dynamic viscosity (DV) at 135oC and kinematic viscosity (KV) at 60oC were conducted to determine the penetration index (PI) and penetration viscosity number (PVN). The results indicate the modified bitumen has better resistance to temperature susceptibility with the additive and better resistance to rutting as it decreases the viscosity of the binder at high temperatures and produces high stiffness modulus as compared to the base bitumen. The study also investigated 126 samples for rheology test of the bitumen using the rolling thin film oven test (RTFOT), pressure aging vessel (PAV), and dynamic shear rheometer (DSR). The results from these tests at high test temperature indicate higher complex shear modulus (G*/sind) with low phase angle (increase stiffness) for aged modified binders indicating better resistance to rutting damage, while at low test temperature they exhibit low complex modulus with high phase angle (decrease stiffness) indicating better resistance to fatigue. The testing on the compatibility and morphology of the modified binders using the scanning electron microscopy test (SEM) were also conducted. The results show the homogeneity of the binder with Sasobit as is completely soluble in the binder with no agglomeration. The study investigated the effect of the warm asphalt additive on the binder aging using Fourier transformation infrared test (FTIR). The results show an insignificant impact on the binder aging. The study prepared and investigated 225 samples of SMA14 and WSMA14 mixtures using the Marshall mix design. The flow and stability tests conducted on the WSMA mixtures show values higher than the minimum JKR/SPJ/2008-S4 specification for SMA in Malaysia with less than 2.5% Sasobit in the three binder sourced investigated. The study recommends up to 2% Sasobit for PEN 80/100, up to 1.5% for PEN 60/70 and 1% for PG 76-22. Based on the penetration test conducted, the two modified PEN bitumen can be categorized as PG 76-22. Also the performance test on the asphalt mix with Sasobit that include rutting and resilient modulus test indicated resistance to rutting damage. Thus, it can be concluded that the Sasobit wax improves bitumen performance, decreases asphalt production temperatures and is feasible to be used in the production of WSMA

Influence of organic wax on bitumen characteristics

The study investigated effect of organic wax Sasobit wax (S) on the characteristics of bitumen 80/100-penetration grade. The consistency of bitumen is measure of its susceptibility to temperature change and resistance to flow which affects ability and resistance to deformation of the mixture. Approach: This study reviewed the bitumen modification process in relation to Warm Mix Asphalt (WMA) technology, using S as a modifier. The study investigated the penetration, softening point and viscosity measurements of modified bitumen 80/100-penetration grade (binder), using the Brookfield viscometer. The binders mixed with various percentage of the wax S 1-5% were investigated. Results: Results from the study showed an increase in softening point, decrease in penetration with an increase in S. The viscosity of binder also decreases at higher temperatures while at midrange temperatures the viscosity increases with an increase in additive. Conclusion: This study has provided a valuable data on the effect of additive S on increasing the kinematic viscosity of binder at low temperature and decreasing the dynamic viscosity at high temperature, been attributed to the presence of S wax with high hydrocarbons molecular content in the binder. Also increasing the additive decreases penetration and increases softening points, The study recommends the use of 2% S for modification of PEN 80/100

Correlation between skid resistance and surface texture for various bituminous roads in Malaysia

The skidding resistance of modern roads. subjected to heavy traffic has become of increasing importance. Skidding resistance is the force generated that resists the sliding of tires on a pavement when the tires are prevented from rotating. The skidding resistance of the bituminous surfaces depends on the frictional properties of the pavement surfaces which includes the microtexture and macrotexture. The microtexture is the interstices o/the aggregate that can resist polishing by traffic. while the macrotexture is the coarse component of the surface aggregate. This study investigated three different bituminous surfaces which includes. asphalt concrete wearing (ACW), stone mastic asphalt (SMA). and surface dressing (SD). Six roads were selected for the study in Johor Bahru and 120 test points on these roads were investigated. using the British pendulum. and sand patch test. The results obtained from the study indicated that the SD surfaces have the highest pendulum test value (PTV) and the general trend is as the PTV increases the texture depth (TD) also increases

Effect of Metakaolin on Strength Properties of Lateritic Soil Intended for Use as Road Construction Material

Abstract. An excellent all-weather road is essential in providing reliable transportation services that comprise social and economic development elements. However, in most cases, the road has to be constructed on a soft foundation soil where large deformations usually occur, which causes increases in maintenance costs and leads to interruption of traffic service, especially during the wet season. It is necessary to stabilize or improve the in-situ soils. This study explores the potential of using metakaolin to improve the geotechnical properties of lateritic soil for road construction materials. The soil classifies as A-6(4) and CL according to the American Association of State Highway and Transport Officials and the Unified Soil Classification System. The soil was treated with 5, 17.5 and 30 % concentrations of metakaolin by dry weight and was compacted using three compaction energies: British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH). California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests were carried out to evaluate the effect of metakaolin on the soil investigated. Results showed a general improvement in the engineering properties of the soil with an increase in metakaolin content, particularly when compacted at the BSH energy level. However, the results did not meet the 1500-3000 kN/m2 7 days UCS criterion stipulated by the Nigerian General Specification for road base courses. However, 30 % lateritic soil/metakaolin blended soil compacted using WAS and BSH energy levels suffice for use as sub-base in road construction, having met the 750-1500 kN/m2 7 days UCS criterion stipulated by the Nigerian General Specification. The Peak CBR value for the treated soil, compacted using the three energy levels of BSL, WAS, and BSH, occurred at 30 % metakaolin concentration with corresponding soaked CBR values of 17, 23 and 31 %. The Nigerian General Specification recommends a nominal strength criterion of a soaked CBR value of 30 and 80 % to be attained by material to be used as sub-base and base course in road construction. Based on the above criterion, only the 30 % metakaolin treated blend compacted at the BSH energy level met the 30 % requirement for sub-base materials